Using sample-path (deterministic asymptotic) analysis, we show that an
input-output process is stable, in the sense that its growth is o(t)
as t approaches infinity, if the exogenous input rate, and the output
rate while the process is in sufficiently large states, are both well
defined and finite and the latter is greater than the former. This gen
eralizes a known result for the workload process in a G/G/1 queue. We
give other examples in which these conditions can be expressed in term
s of primary quantities and thus checked a priori.